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HomeMy WebLinkAboutDrainage Reports - 12/01/1984i FINAL DRAINAGE REPORT 1 w. FOR ' PROVINCETOWNE/PORTNER S.I.D. ' CITY OF FORT COLLINS .COUNTY,OF LARIMER ' STATE OF COLORADO DECEMBER, 1984 Prepared by: Parsons & Associates Consulting Engineers 432 Link Lane Plaza ' Fort Collins, Colorado 80524 Project Number 64.08 S.I.D. TABLE OF CONTENTS DESCRIPTIVE REPORT General Introduction Site Description Proposed Land Use Hydrologic Analysis Hydraulic Analysis Detention. BASIN FLOW PATTERN SCHEMATIC DIAGRAM CORRESPONDENCE LIST DESIGN POINT DESIGN FLOWS HYDROLOGY CALCULATIONS South Basin Middle Basin North Basin Road Section Composite Runoff Coefficients DRAINAGE MAP 0 I ' FINAL STORM DRAINAGE REPORT PROVINCETOWNE/PORTNER S.I.D. 1 FORT COLLINS, COLORADO IGENERAL This report, in combination with the Drainage Map accompanying this ,. report, the Provincetowne/Fortner S.I.D. Design Plans, and the Fossil Creed, Drainage Basin Master Drainageway Planning Study is intended to describe the procedures and results of a study of stormwater runoff generated by this project and adjacent properties. The proposed development along with the required drainage improvements are analyzed in accordance with the guidelines established by the City of Fort Collins' Storm Drainage Criteria Manual. INTRODUCTION ' The purpose of this study is to determine the quantity of stormwater runoff generated from the development of the various tracts within the Provincetowne/Fortner site, along with adjacent upstream property, and the manner by which this runoff will be accommodated by the Provincetowne/Fortner S.I.D. SITE DESCRIPTION The site is loacted in the eastern 1/2 of Section 13, Township 6 ' North, Range 69 West, of the 6th Principal Meridian, State of Colorado, Count.y of Larimer. The Provincetowne/Fortner project consists of 409.7 acres more or less and is bounded by Trilby Street on the north, Lemay Road on the east, Windsor Road on the south, and the Moberly Heights and Victoria Estates developments and the Murr, Bernhardt, and Hamer properties to the west. ' The site is presently undeveloped and is used primarily for agricultural purposes. The existing drainage pattern flows to the north and east at slopes ranging from 0.5 to 6 percent. The Robert Benson Late irrigates the majority of the property. The Basin Flow Pattern Schematic Diagram describes the overall drainage pattern (use in conjunction with the Drainage Map). IPROPOSED LAND USE The project is planned to consist of tracts on which varying ' proposed land uses will occur including: a variety of Residential Development in the low to medium density range, Commercial/Retail uses, Business Services, Industrial/Tech Park, City Parks, and ' scenic stormwater detention facilities. HYDROLOGIC ANALYSIS The Rational Method and the Colorado Urban Hydrograph Method have been utilized to calculate stormwater runoff flows for the 2-5 10-; and 100-year developed return period storms for the various tracts in Provincetowne/Portner. The Drainage Map identifies the basin boundaries, design points, and summarizes the results of the hydrologic analysisof these sub -basins. In addition, offsite stormwater contributes runoff to the Robert Benson Detention Lake and was considered to release at a controlled rate into the a development. It should be noted at this point that the calculated flows in Provincetowne/Portner are approximate since details of the interior drainage patterns, street layouts, and building locations within individual tracts have not been permanently established. However, this report is based upon the best data available at this time. it ' is the intent of the developer to maintain the flow patterns and basin configurations presented herein as much as possible. Where changes are made in future projects, detailed drainage studies will ' be made and appropriate revisions to this report will be recommended. HYDRAULIC ANALYSIS i Once the runoff volumes from the site were -estimated, various combinations of flows were used to side the storm sewer system to be built as part of this S.I.D. That runoff which does not enter this system from street inlets is captured by an array of temporary swales and conveyed to the storm sewers. The inlets included in this -design are only as numerous as necessary for this intermediate development. As further tracts develop, the storm sewer system will be extended and additional inlets will be designed as required. As ' the storm sewer system expands, the temporary swales will be eliminated. In addition to storm sewer and swale sizing, street inundations due to the major storms were computed. It was found that if on -site detention is provided on developed tracts within Provincetowne/Portner then street inundation can be kept within the limits of City design criteria at all design points. DETENTION No detention facilities are included in this S.I.D. excepting the ' transient storage provided in the temporary drainage swales during major storm events. However, complete detention is assumed to exist and to be maintained within Robert Benson Lake for its entire basin both now and after its dam relocation. Design flows herein have assumed no greater than minor storm release under al.l circumstances. Furthermore, this report assumes that on -site detention will be provided as tracts are developed throughout the Provincetowne/Fortner project and the drainage facilities included in this S.I.D. have been sized accordingly. n&.t YJ- -----J hn D. Mi n fy of ey-". t+Jynne, P 14961 a 0 f 14961 Pam, m ��.asfi ✓F f,Q� Ua� I ' FLOW PATTERN SCHEMATIC DIAGRAM Legend: Hydraulic Design Point/Local Drainage Basin Drainage Structure > Target ' Local Acreage / Accumulated Acreage Location ' N.A. = Not Applicable V.E. = Victoria Estates SOUTH BASIN Bristol Rd 22/E-2 Windsor Rd I1/E-1 Stanton 8.08/N.A. 5.17/13.25 Creek ' MIDDLE BASIN 25/A-1 U.S. 287 21/A-2 Benson Dam ' 190.26/N.A. 138.74/329.00 (Controlled Release) 24/V.E. Prop. Line 1/B-1 Bristol Rd., 20/B-2 ' 44.0/N.A. 7 .6/429.44 5.10/484.5 " (D Lemay Rd Unnamed Tributary to Stanton Creek NORTH BASIN ' 4/C-3 Province Dr 20.23/N.A. ' 2/C-1 Province Dr 3/C-2 Brittany. Or 8/C=4 Ridge Ln5/D-3 11.09/1028.8 13.28/N.A. 5.31/56.81 10.43/87.47 ' 9/D-2 Brittan Rd 7/D-1 Brittany Rd 18.30/N.A. 4.32/N.A. ' © Granville Or 6/D-4 Lemay Rd Drainage Along 34.19/155.37 Trilby Rd I CORRESPONDENCE LIST DESIGN POINT BASIN INLET SEWER LINE STREET / DESCRIPTION 1, 1.1 - 1.4 B-1 192518919 A, A-1 Bristol Drive 2, 2.1 C-1 3 C Province Rd, manhole for future connect. 3, 3.1-3.3 C-2 4916917 D, D-1 Brittany Drive 4, 4.15 4.2 C-3 59 6 E Province Road 59 5.1, 5.2 D-3 99 10 G Granville Drive 6 -" D-4 Future Lemay Avenue 7.1, 7.2, 7.3 D-1 72 8. F, F-1 Granville Drive, Brittany Drive 8.1, 8.2 G-1 16A916B. L Rumford Place 9, 9.1, 9.2 D-2 14, 15 1 Brittany Drive 102 10.1-10.3 D-2 11912913 H, I Brittany Drive 11 E-1 M Bristol Drive 12 D-2 channel E. Summer Drive 13 iG-1 exist. K Trilby Road 14 15 16 R.Benson B Bristol Drive, Irrigation ditch 17 18 C-4 swale Control section for Lemay swale 19 20 B-2 Future Lemay Avenue 21 A-2 R. Benson Lake control structure 22 E-2 Future Windsor Road 23 E-3 exist. Windsor Road, South Victoria Estates culvert 24 V.E. none 25 A-1 exist U.S. 287, Del Webb development culvert, inlets ' DESIGN POINT ' SOUTH BASIN 11 ' 22 MIDDLE BASIN 25 21 24 ' 1 20 ' 10 ' NORTH BASIN 2 4 7 ' 18 9 ' 6 1 DESIGN POINT DESIGN FLOW RETURN EVENT DESIGN FLOW STRUCTURE FLOW (YR) (CFS) REMARKS 2 6.1 storm sewer 10 74.4 culvert Flow=120%xcumulative 100-yr 2 3.4.7 storm sewer Historic release,D.Webb Deg _< 2 < 34.5 Dam Outlet Struct. Controlled release 100 132.0 None Offsite drainage V.E. 10 110.9 Storm sewer Flow=10yr cumulative +. R.Benson release 2 27.3 Storm sewer Historic release Middle Basin N/A :!�. 35 Irrigation Downstream pond elev. maintenance 2 5.9 storm sewer 2 26.4 storm sewer Flow=cumulative 2 yr 10 72.2 storm sewer 1100 13.8 storm sewer 100 240.1 swale Flow=cumulative 100 yr 2 61.5 storm sewer Flow=cumulative 2 yr 2 14.9 storm sewer 2 20.4 storm sewer Historic release, North Basin I FORMULAE Time of Concentration: ' 1.87(1.1 - Ccf)D'S Where: C = Runoff. Coefficient T = c D = Distance in feet S.33 S = Slope in percent cf =.Antecedent precipitation factor ' 1.0 for 2-year and 10-year 1.25 for 100-year. Velocity and Capacity: 1'487 X R-67 X so Where: n: = Manning roughness coefficient ' V = n A = Cross -sectional area in square feet Q = 1'n86 X A X R'67 X S'S R = S = Hydraulic radius Slope in feet per foot Runoff Quantities: Q = CIAcf Where: C = I = Runoff Coefficient Rainfall intensity, inches -per hour A = Area in acres ' cf = Antecedent precipitation factor 1.0 for 2=year and 10-year 1,25 for 100-year ' Runoff Volume: V = Q X .Tc X 60 Where: Q = Runoff in cubic feet per second. T = Time of concentration c. Orifice Plate: Q = 0.65A f2gh Where: A = Cross-section area in square feet g = Acceleration due to gravity, ' 32 feetA ec.2. h =.Height of water above center 1 Of opening ' Detention: Volume is computed by means of a program, using the Modified Rational Method which varies the rate of flow in, while dis- charging at.a constant rate. HYDROLOGY CALCULATIONS SOUTH BASIN Design Point 11, Basin E-1 Area = 8.08 Ac. Length = 1150 Ft. C = 0.20 Undeveloped 2-YR 10-YR Height = 27 Ft. Slope = 2.35% 100-YR Tc = 42.9 min. Tc = 42.9 Tc = 40.5 I = 1.15 in/hr I = 2:05 I_ . = 3.40. Q = 1.9 cfs Q = 3.3 Q = 6.9 - C = 0.50 Developed Tc = 28.6 Tc = 28.6 Tc = 22.7 I = 1.50 I = 2.65 I = 4.85 Q = 6.1 Q = 10.7 Q = 29.4 Design Point 22, Basin E-2 Area = 5.17 Ac. Length = 750 Ft. C = 0.20 Undeveloped 2-YR 10-YR Tc = 35.8 min. Tc = 35.8 I = 1.3 in/hr I = 2.3 Q = 1.3 cfs Q = 2.4 C = 0.85 Developed Tc = 10.0 Tc = 10.0 I = 2.50 I = 4.40 Q = 11.0 Q = 19.3 Cumulative: Basins E-1, E-2 Area = 13.25.Ac. Length = 1400 Ft. C = 0.20 Undeveloped 2-YR 10-YR Tc = 47.30 Tc = 47.30 I = 1.08 in/hr I = 1.63 Q = 2.9 cfs Q = 4.3 Height = 16 Ft. Slope = 2.13% 100-YR Tc = 33.8 I = 3.85 Q = 5.0 Tc = 4.0 I = 9.50 Q = 52.2 Height = 33 Ft. Slope = 2.36% 100-YR Tc = 44.7 I = 3.23 Q = 10.7 HYDROLOGY CALCULATIONS - 2 Cumulative: Basins E-1, E-2 (Continued) C = 0.64 Composite Developed 2-YR 10-YR 100-YR Tc = 24.2 Tc = 24.2 Tc = 15.8 I = 1.65 I = 2.90 I = 5.85 Q = 14.0 Q = 24.6 Q = 62.0 MIDDLE BASIN Design Point 25, Basin A-1 Area = 190.26 Ac. Length = 3500 Ft. Height = 100 Ft. Slope = 2.86% C = 0.22 Composite Undeveloped 2-YR 10-YR 100-YR Tc = 68.6 min. Tc = 68.6 Tc = 64.2 I = 0.83 in/hr I = 1.46 I = 2.45 Q = 34.7 cfs Q = 61.1 Q=.128.2 C = 0.58 Estimated Composite Developed (Webb Master Plan 9/5/84) -Tc = 40.53 Tc, = 40.53 Tc = 29.23 I = 1.20 I = 2.15 I =.4.22 Q = 132.4 Q = 237.3 Q = 582.1 D P' t 21 B' A 2 esign oin , UZI Area = 138.74 Ac. Length = 1700 Ft. Height = 46 Ft C = 0.23 Composite Undeveloped 2-YR 10-YR Tc = 48.2 min. Tc = 48.2 I = 1.08 in/hr I = 1.90 Q = 34.5 cfs Q = 60.6 C = 0.44 Composite Developed Tc = 36.5 Tc = 36.4 I = 1.30 I = 2.30 Q = 79.4 Q = 140.4 Slope = 2.70% 100-YR Tc = 45.0 I = 3.25 Q = 129.6 Tc = 30.5 I = 4.13 Q = 315.1 HYDROLOGY CALCULATIONS - 3 Design Point 24, Basin-V.E. Area = 44.0 Ac. Length = 2200 Ft. Height = 53 Ft. Slope = 2.41% C = 0.45 Current Development 2-YR 10-YR 100-YR Tc = 42.5 min I = 1.20 in/hr Q = 23.8 cfs Tc = 42.5 I = 2.10 Q = 41.6 C.= 0.50 Future Development Tc = 39.3 Tc = 39.3 I = 1.22 I = 2.20 Q = 26.8 Q = 48.4 Design Point 1, Basin B-1 Area = 49.6 Ac Length = 1500 Ft. C = 0.20 Undeveloped 2-YR 10-YR Tc .= 50.9 min. I = 1.03 in/hr Q = 10.1 cfs Tc. = 35.2 I = 3.75 Q = 92.8 Tc = 31.1 I = 4.08 Q = 132.0 Height =-32 Ft. Slope = 2.10% Tc = 150.9 I = 1.83 Q = 18.0 C = 0.45.Composite Developed Tc = 36.8 Tc = 36.8 I = 1.28 I = 2.28 Q = 28.6 Q = 50.9 Design Point 20, Basin B-2 Area = 55.10 Ac. Length = 1400 Ft. C = 0.20 Undeveloped 2-YR 10-YR Tc = 54.4 min. I = 1.00 in/hr Q = 11.0 cfs Tc I Q = 12.5 = 2.30 = 101.9 Tc = 54.4 I = 2.70 Q = 29.8 C = 0.85 Developed Tc = 12.5 I = 3.30 Q = 146.1 Tc Q T c Q Height = 38 Ft. 100-YR = 48.1 = 3.09 = 38.0 = 30.4 = 4.13 = 115.2 Slope = 2.71% 100-YR Tc = 51.4 I = 2.90 Q = 39.9 Tc = 5.0 I = 9.00 Q = 498.2 I 1 11 1 1 HYDROLOGY CALCULATIONS - 4 Cumulative: Basins A-1, A-2 Area = 329.00 Ac. Length='.6500 Ft. Height = 107 Ft. Slope = 107(0.8*6500)=2.06% Peak Flow, Undeveloped Condition CUHP with Impervious Area = 34% estimated 2-YR 10-YR 100-YR Qp = 82.6 cfs Qp = 326.2 Qp = 640 Vol = 7.4 Ac-Ft Vol = 24.2 Vol = 46.3 Peak Flow, Developed CUHP with Impervious Area = 50% estimated 2-YR 10-YR 100-YR Qp = 196.8 cfs Qp = 370.4 Qp = 687.0 Vol ,= 20.5 Ac-Ft Vol = 28.1 Vol = 51.2 Cumulative: Basins B-1, V.E. Area = 93.6 Ac. Length = 3400 Ft.. Height = 60 Ft. C = 0.32 Composite, Undeveloped 2-YR 10-YR Tc = 70.4 min. Tc = 70.4. Tc I = 0.82 in/hr. I = 1.43 I Q = 24.6 Q = 42.8 Q C = 0.48 Composite Developed Tc = 56.0 Tc = 56.0 Tc I = 0.96 I = 1.70 I Q = 43.1 Q = 76.4 Q Cumulative: Basins B-1, B-2, V.E. Area = 148.7 Ac. Length = 4900 Ft. Height = 85 Ft. C = 0.27 Composite Undeveloped 2-YR 10-YR Tc = 90.5 Tc = 90.5 Tc I = 0.68 I = 1.19 I Q = 27.3 Q = 47.8 Q C = 0.62 Composite Developed Tc = 52.3 Tc = 52.3 Tc I = 1.00 I = 1.78 I Q = 40.1 Q = 71.5 Q Slope = 1.76% 100-YR = 63.2 = 2.49 = 93.2 = 45.2 = 3.23 = 181.4 Slope = 1.73% 100-YR = 83.1 = 1.98 = 228 = 35.4 = 3.76 = 433.3 HYDROLOGY CALCULATIONS - 5 NORTH BASIN Design Point 2, Basin C-1 Area = 13.28 Ac. Length = 1000 Ft. C = 6.20 Undeveloped 2-YR 10-YR Tc = 43.8 min. I = 1.15 in/hr Q 2.8.cfs Height = 18 Ft. Slope = 1.80% Tc = 43.8 I = 2.00 Q = 4.8 C = 0.34 Composite Developed 100-YR Tc = 41.3 I = 3.40 Q = 10.2 Tc = 36.9 Tc = 36.9 T I = 1.30 I = 2.30 c I Q = 5.9 Q = 10.4 Q Design Point 3, Basin C-2 Area = 45.31 Ac. Length = 2800 Ft. Height = 53 Ft. C = 0.20 Undeveloped 2-YR 10-YR Tc = 72.0 min. Tc = 72.0 I = 0.80 in/hr I = 1.40 Q = 7.2 :cfs Q = 12.'5 C = 0.48 Composite Developed Tc = 49.6 Tc = 49.6 I = 1.05 I = 1.87 Q = 22.8 Q = 40.7 Design Point 4, Basin C-3 Area = 20.23 Length = 1100 Ft. C = 0.20 Undeveloped 2-YR 10-YR Tc = 41.9 min. Tc = 41.9 I = 1.20 in/hr I = 2.10 Q = 4.9 cfs Q = 8.5- C = 0.85 Developed Tc = 11.6 Tc = 11.6 I = 2.40. I = 4.20 Q = 41.3 Q = 72.2 Tc I Q- Tc I Q Height = 26 Ft. = 32.8 = 3.95 = 22.3 Slope = 1.89% 100-Yr = 68.0 = 2.40 = 10.2 = 40.0 = 3.50 95.2 Slope = 2.36% 100-YR Tc = 39.6 I = 1.25 Q = 17.7 Tc = 4.7 I = 9.10 Q = 196.6 HYDROLOGY CALCULATIONS - 6 Design Point 18, Basin C-4.•` Area = 10.43 Ac. Length = 950 Ft. Height = 17 Ft. Slope = 1.79% C = 0.20 Undeveloped 2-YR 10-YR 100-YR Tc = 42.7 min. Tc = 42.7 Tc = 40.3 I = 1.15 in/hr I = 2.05 I = 3.45 Q = 2.4 cfs Q = 4.3 Q = 9.0 : C = 0.76 Composite Developed Tc = 16.1 Tc = 16.1 Tc = 7.1 I = 2.05 I = 3.60 I = 8.1 Q = 16.2 Q = 28.5 Q = 80.2 Design Point 7, Basin D-1 Area = 4.32 Ac. Length = 850 Ft: Height = 19 Ft. Slope = 2.24% C = 0.20 Undeveloped 2-YR 10-YR 100-YR Tc = 37.5 min. Tc = 37.5 Tc = 35.4 I = 1.30 in/hr I = 2.25 I = 3.75 Q = 1.1 cfs Q = 1.9 Q = 4.1 C = 0..5 Developed Tc = 25.0 Tc = 25.0 Tc = 19.8 I = 1.60 I = 2.85 I = 5.10 Q = 3.50 Q = 6.20 Q = 13.9 Design Point 5, Basin D-3 Area = 11.09 Ac Length = 1100 Ft. Height = 34 Ft. C = 0.20 .Undeveloped 2-YR 10-YR Tc = 38.3 min. Tc = 38.3 I = 1.30 in/hr I = 2.20 Q = 2.9 cfs Q = 4.9 C = 0.49 Composite Developed Tc = 26.0 Tc = 26.0 I = 1.60 I = 2.80 0 = 8.7 Q = 15.2 Slope = 3.09% 100-YR Tc = 36.2 I = 3.70 Q = 10:3 Tc = 20.8 I = 5.10 Q = 34.6 HYDROLOGY CALCULATIONS - 7 Design Point 9, Basin D-2 Area = 18.30 Ac Length = 1700 Ft. C 0.20 Undeveloped 2-YR 10-YR Tc = 49.1 min. Tc = 49.1 I = 1.05 in/hr I = 1.85 Q = 3.8 cfs Q = 6.8 C = 0.55 Developed Tc = 30.0 Tc = 30.0 I: = 1.48 I = 2.60 Q = 14.9 Q = 26..2 Design Point 6, Basin D-4 Area = 34.19 Ac. Length = 1800 Ft. C = 0.20 Undeveloped 2-YR 10-YR Tc = 46.3 min. Tc = 46.3 I = 1.10 in/hr I = 1.95 Q = 7.5 cfs Q = 13.3 C = 0.55 Developed - Height ' = 48 Ft. Slope = 2.82% 100-YR Tc Q Tc Q Height = 66 Ft. = 46.4 = 3.10 = 14.2 = 22;5 = 4.87 = 61.3 Slope = 3.67% 100-YR Tc = 43.7 I = 3.25 ' Q = 27.8 Tc = 28.3 Tc = 28.3 Tc = 21.2 I = 1.50 I = 2.67 I = 5.05 Q = 28.2 Q = 50.2 Q = 118.7 Cumulative: Basins C-1, C-2 Area='58.61 Ac. Length .= 2800 Ft. Height = 53 Ft. Slope = 1.89% C = 0.20 Undeveloped 2-YR 10-YR 100-YR Tc = 72.0 min. Tc = 72.0 Tc = 68.0 I = 0.80 in/hr I = 1.40 I = 2.40 Q = 9.4 cfs Q = 16.4 Q = 35.2 C = 0.45 Composite Developed Tc = 52.0 Tc = 52.0 Tc = 43.0 I = 1.00 I = 1.80 I = 3.33 Q = 26.4 Q = 47.5 Q = 109.8 HYDROLOGY CALCULATIONS - 8 Cumulative: Basins C-1, C-2, C-3, C-4 Area = 89.25 Ac. Length. .= 4000 Ft. Height = 74 Ft. C = 0.20 Undeveloped 2-YR 10-YR Slope = 1.85% 100-YR Tc = 86.7 min. Tc = 86.7 Tc = 81.9 I = 0.70 in/hr I = 1.21 I = 2.01 Q = 12.5 cfs Q = 21.6 Q = 44.8 C = 0.58 Composite Developed Tc = 50.1 Tc = 50.1 Tc = 36.1 I = 1.04 I = 1.75 I = 3.71 Q = 53.8 Q = 90.6 Q = 240.1 Cumulative: Basins C-1, C-2, C-3, C-4, D-1, D-3 Area = 104.66 Ac. Length = 4055 Ft. Height = 90 Ft.. Slope = 2.22% C = 0.20 Undeveloped 2-YR 10-YR 100-YR Tc. = 82.2, min. Tc = 82.2 Tc = 77.6 I = 0.72 in/hr I = 1.28 I = 2.10 Q = 15.1 cfs Q = 26.8 Q = 54.9 C = 0.56 Composite Developed Tc = 49.3 Tc = 49.3 Tc I = 1.05 I = 1.89 I Q = 61.5 Q = 110.8 Q Cumulative: Basins C-1, C-2, C-3, C-4, D-1, D-2, D-3, D-4 Area = 157.15.Ac. Length = 5405.Ft. Height = 120 Ft. C = 0.20 Undeveloped 2-YR 10-YR Tc = 94.8 min. I = 0.65 in/hr Q = 20.4 cfs Tc I Q = 56.9 = 0.94 = 82.7 T = 94.8 c I = 1.13 Q = 35.5 C = 0.56 Composite Developed Tc = 56.9 I = 1.69 Q = 148.7 Tc I Q Tc I Q = 36.5 = 3.71 271.8 Slope = 2.22% 100=YR = 89.6 = 1.87 = 73.5 = 42.2 = 3.38 = 371.8 ' HYDROLOGY CALCULATIONS - 9 ' NORTH BASIN Design Point 17, Basin C-3A Area = 10.01 Ac. Length = 1350.Ft. Height = 17 Ft. C = 0.20 Undeveloped 2-YR 10-YR ' Tc = 57.3 min T� 57.3 I = 0.95 in/hr I = 1.68 ' Q = 1.9 cfs Q = 3.4 C = 0.85 Developed ' Tc = 15.9 min Tc = 15.9 I = 2.05 I = 3.62 Q = 17.4 Q = 30.8 ' Design Point 4, Basin C-3E ' Area = 10.22 Ac. Length = 900 Ft. Height = 15 Ft. ' C = 0.20 Undeveloped 2-YR 10-YR ' Tc = 42.6 min Tc 42.6 I = 1.17 in/hr I = 2.10 Q = 2.4 Q = 4.3 ' C = 0.85 Developed Tc = 11.8 min Tc = 11.8 I = 2.32 I = 4.10 ' Q = 20.2 Q = 35,6 Slope = 1.26% 100-YR Tc = 54.1. I = 2.81 Q = 7.0 Tc= 6.4 I = 8.30 Q = 88.3 Slope 1.67% 100-YR Tc = 40.2 I 3.49 Q = 8.92 Tc = 4.7 I = 9.10 Q = 98.8 HYDROLOGY CALCULATIONS ROAD SECTION COMPOSITE RUNOFF COEFFICIENTS ' Bristol Drive ' Inlets # 19 18: C = (331(0.95) + 7'(0.25))/40'=0.83 for 6+06 to 21+38 (15321) Inlets # 29 19: C = (291(0.95) + 11'(0.25))/4O'=0.76 for 6+12 to 21+33 (15211) Inlet # 3: C = 0.83 for 21+38 to 25+56(418') C = (33'(0.95)+4'(0.25))/37'=0.87 for 25+56 to 27+35 (1791) ' C = 0.93 for 27+35 to 27+87 (52'); Province C = 0.20 for offroad Province Road Inlet # 17: C = 0.76 for 21+33 to 25+56 (423') Bristol ' C = (41'(0.95)+4'(0.25))/45'=O.89 for 25+56,yo ` 27+35 (179') Bristol C = 0.93 for 27+35 to 27+87 (52') Bristol C = (36'(0.95) +4'(0.25))/40'=0.88 for 8+63 to 11+44 (281') Inlet # 5 C = 0.88 for 8+24 to 8+63(39') ' C = 0.76 for 2+74 to 8+24 (550') C = 0.89 for 0+62 to 2+74 (2121) C = 0.93 for 0+40 to 0+62 (221) ' C = 0.75 for Lemay Inlet # 6 C = (35'(0.95)+6'(0.25))/41'=0.85 for 24+23 to 24+53 (20') Brittany C = 0.93 for 24+53 to 25+05 (52') Brittany ' C = (391(0.95)+11(0.25))/40' = 0.93 for 8+24to. 8+50 (261). C = 0.83 for 2+74 to 8+24 (550') C = 0.87 for 0+62 to 2+74 (2121) ' C = 0.93 -fo'r 0+40' to _0+62 (22' ) C.= 0.75 for Lemay ' Brittany Drive Inlet # 4: C = 0.93 for 8+94 to 12+28 (334') Province C = 0.20 for offroad ' C = (39'(0.95)+2'(0.25))/41'=0.92 for 22+71 to 24+52 (1811) C- 0.93 for 24+52 to 25+05 (53') C = (27'(0.95)+1O'(0.25))/37'=O.76 for 19+21 to 22+71 (3501)• Inlet # 16 C = (231(0.95) + 10'(0.25))/33'=0.74 for 22+71 to 24+52 (1811) ' C = (23'(0.95) + 14'(0.25))/37'=0.69 for 19+28 to 22+71 (343') ' Granville Drive Inlet # 9 C = (22'(0.95)+5'(0.25))/27'=0.82 for 0+35 to 10+22 (987') C = 0.75 for Lemay Inlet # 10 C = 0.82 for 0+35 to 10+01 (9661) C = 0.75 for Lemay C = 0.69 for 17+67 to. 19+28 (161') Brittany C = 0.74 for 15+95 to 17+67 (172') Brittany Inlet # 7 C = 0.82 for 10+37 to 17+82 (745') C = 0.20 offroad ' Inlet # 8 C = 0.82 for 10+37 to 17+82 (7451) C = 0.50 offroad C = 0.92 for 16+35 to 19+21 (2861) Brittany ' C = 0.93 for 16+22 to 16+35 (131) Brittany PROVINCETOWNE/PORTNER \ ' { I I . e �• •\, t �\ , i , } \ I I ; ' ESTATES SOUTH ELm ti L `�� _ Y-I 4 �\� jt '0. �4 \r "j I♦;\`L4 C .j Qo Oc SIQ f L :: I�-' -1 •_�_ yyI((T~ � _ .`1 ��G b�!l/�/L•^`1VJQ/f� PrP �GQ4J/� I�NA•N11 y,,R/ rW/1 b .. �NJ�M�GlIlY,/I�IGJ/ e-VeI1y�1@�f!i�W�/,D Y.A� •,i/lI I S , \\. \\\ :\ \\\\\• �\ \ \\\ \. \ `\ opment Inc. 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WAX Cook. ncr ow •� • .._-. • _. _ .. / j •. \ RAILROAD •Aw . � '. __' ._ . p I ` I STREAM - c 1 '•/J ! .. ��� l ` ) E DITCH MIACULVERT HEADWALL 7 a•o 21 12M ' BUILDING E IN� M!ITOUTLINE POPIER-TELE POLE �_ _ '-\ Y\ .1• JI' � , ,a� ^�' STORM SEWER LINE \ J. �_��__�` '\ ,•_`� \,4 / i' - �2 DESIGN POINT INLET DESIGN POINT ' •• \♦` �_-'� i �� ,Z11,BASIN � BOUNDARY PROPERTYLINE ' �. —'"F �• ,"�--. :° (/!W. � �.. �/�I 200 0 200 400 600 •' `, '•� ll //�. �. �� �— / :,� � SCALE' I•• 400'1 CONTOUR INTERVAL, 2 FEET 1 TOPOGRAPHY Ot•1 THIS MAP COMPLIES VlRTf NATIONAL MAP ACCURACY STANDARDS... 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